Looks quite reminiscent of the Richter-Rauzer line 6. Bg5 e6 7. Qd2 Be7 8. 0-0-0 0-0 9. f4 Nxd4 10. Qxd4 Qa5 11. Bc4 Bd7, in which there's some old book stuff with Black playing ...Bc6, ...h6, ...Qh5 and getting in ...d5 with the help of a rook coming to d8.

I'm glad you posted this question because I'm very surprised there are no books that even discuss this 4.Qxd4 line. I'm surprised this doesn't get classified as a anti Sicilian. This variation isn't mentioned in Dangerous Weapons for the Sicilian nor is this discussed in Experts against the Anti Sicilians book. I can only hope the upcoming Kotronias book on the anti Sicilian lines sheds some light on this.